1. Field of the Invention
The present invention relates to a refrigerant composition used in refrigerators or other similar machines and also relates to a method of producing the refrigerant composition. More particularly, the present invention relates to a refrigerant composition containing at least a refrigerant gas composed of a paraffin hydrocarbon, a silicone oil, and an ether.
2. Description of the Background Art
A typical refrigerator has a compressor, a condenser, an evaporator, a receiver, an oil separator, a liquid separator, etc., which constitute a refrigerating cycle. The purpose of a refrigerator is to absorb heat from a low temperature heat source and to release the heat where the temperature is high, which resembles the use of a pump to raise water to a higher place. Therefore, the refrigerator is also called "heat pump".
Meantime, when the purpose of a refrigerator is to release heat into a high-temperature heat source so as to use it for heating, the system is also called "heat pump air conditioning unit". A refrigerant used in the refrigerating cycle is evaporated at low temperature in the evaporator to form a high-temperature, high-pressure gas, which is then cooled in the condenser to return to a liquid refrigerant. In this way, the refrigerant circulates in the refrigerator, thereby continuously performing a refrigerating operation. Typical examples of refrigerants used for this purpose include ammonia, carbon dioxide gas, chlorofluorohydrocarbon (hereinafter occasionally referred to as "CFC") gases, that is, fluorine-containing carbonized compounds [Freon (Flon) gases] such as R-11, R-12, R-13, R-21, R-22, R-113, R-114, R-500 and R-502, propane, etc.
CFC gases, i.e. Freon gases, and ammonia are mainly used as refrigerants. Freon gases are also used as an azeotropic refrigerant which is formed by mixing together two different kinds of Freon gas, but which functions as if it were composed of only one kind of Freon gas. However, ammonia is a toxic, combustible and explosive gas although it is excellent in refrigerant characteristics such as refrigerating capacity. Moreover, ammonia corrodes copper and a copper alloy when air and water content get mixed in it.
In contrast, Freon refrigerants are excellent in refrigerant characteristics such as refrigerating capacity as well as non-combustible and non-explosive, and they are neither corrosive with respect to metals nor toxic to the human body. Accordingly, Freon gases are superior refrigerants. However, since it became clear that Freon gases destroy ozone (O.sub.3) in the stratosphere, specific Freons, i.e. R-11, R-12, R-113, R-114 and R-115, have become subject to regulations. R-12 is mainly used in relatively small-sized refrigerating machines such as automobile air conditioners and domestic refrigerators. R-22 (hereinafter occasionally referred to as "HCFC" Freon) is used in medium-and large-sized compressors because the refrigerating capacity per unit volume is larger than that of R-12.
The "HCFC" Freon will also become subject to regulations. R-113 and R-114 are mainly used in turbo-refrigerators. A mixture of Freon gases, for example, R-115 and R-22, is used as a refrigerant for low-temperature use application in the form of azeotropic refrigerant R-502. At any rate, R-22 may also become subject to regulations in addition to the above-described Freons. In such a case, all the Freons and Freon-containing azeotropic refrigerants will become unusable.
In refrigerators, a refrigerating machine oil is used as a lubricant for protecting the compressor and other constituent elements from wear. It is demanded to use a refrigerating machine oil which does not lose its lubricating properties even at low temperature and which can stably coexist with a refrigerant. In the case of a Freon refrigerant, the liquid refrigerant and the refrigerating machine oil are soluble in each other up to a certain temperature. A Freon refrigerator is designed so that the refrigerating machine oil is discharged from the compressor and returned to the crank case thereof after circulating through the system. Thus, the refrigerator is capable of automatic operation. When a compressor that needs a large amount of refrigerating machine oil is used, or when the refrigerant piping distance is long, an oil separator is used.
Under these circumstances, various Freon substitutes have been proposed. However, many of these proposals are concerned with substitute Freons for "HCFC" Freons such as R-22, R-123, etc., which are not subject to regulations for the moment, and azeotropic refrigerants formed by mixing together these substitute Freons. Accordingly, none of the Freon substitutes have characteristics adequate to completely substitute for the existing Freon refrigerants. There have been proposed domestic refrigerators that use a non-azeotropic refrigerant other than Freon, for example, propane. However, this type of refrigerator involves problems in terms of combustibility and explosiveness.
Japanese Patent Application Unexamined Publication (KOKAI) No. 5-339563 proposes a flame-retarded refrigerant which consists essentially of LPG and a silicone added thereto, or a refrigerant consisting essentially of an alcohol, LPG, propane or butane, and an aqueous silicone added thereto. However, such refrigerants cannot be used for refrigerators that are originally designed to use Freon refrigerants, such as the existing domestic refrigerators and automobile air conditioners. That is, the new refrigerants do not match this type of refrigerator in terms of the capacity of the compressor used in the refrigerator, i.e. the compression efficiency, and power required to operate the compressor.
To use these newly proposed refrigerants, the basic design of the compressor and other constituent elements of the refrigerator must be changed. The design change causes the cost to increase exceedingly, resulting in a waste of resources. It would cost immeasurably to dispose of the existing automobile air conditioners and refrigerators that use Freon refrigerants and of production facilities for these refrigerating machines or to change the production facilities.